S14 Speedo dies after 30mph

[John1006]

As the title states, after going over 30mph it will just drop to 0. When I slow down to 30mph it comes back and works perfectly from 0-30 or 30-0. It's a 95 S14 with an S14 SR swap. Brand new speed sensor from Nissan, swapped a buddies sensor over, and swapped a different cluster in. All with the same outcome.

[2.5T_/<ouki]

As the title states, after going over 30mph it will just drop to 0. When I slow down to 30mph it comes back and works perfectly from 0-30 or 30-0. It's a 95 S14 with an S14 SR swap. Brand new speed sensor from Nissan, swapped a buddies sensor over, and swapped a different cluster in. All with the same outcome.

In for results. I'm having a similar issues but complete opposite if that makes sense. If i'm stopped it reads 0mph and when I start driving it jumps up to 40mph and will stay at 40mph no matter how fast I go.

[John1006]

Have you tried a different cluster also?

[brndck]

sounds like a wiring issue, or perhaps the teeth on the gear (on the trans side, not the sensor side) are fucked up? the gear (again, on the trans side, not the sensor side) could be damaged, and spinning on the shaft instead of spinning WITH the shaft.

[John1006]

I feel like it could be wiring related, but then I jumped the sensor straight to the cluster and still same outcome.

[John1006]

Bump: Anyone else have any other ideas besides my tranny being fucked? Lol

[John1006]

Bump.......

[2.5T_/<ouki]

Have not tried another cluster but almost guarantee it's a cluster issue. I can tap the top of the cluster or the dashboard and I see it jump to where it should be. I do have another one I'm waiting to swap in, however I've only got 170 miles on my new engine and that's how I'm keeping track of the "break-in" period lol.

[DJTTon]

This is not a suggested plan of action, just a flow of action. Take the steps in your preferred order.

I think you should get under the car and inspect the speed sensor and the transmission gear that spins it. Just be careful because pulling out the VSS (vehicle speed sensor), will cause tran. fluid to blurt out so be prepared with a pan; let all of the fluid drip out. See if you can stand the car off the ground, using reliable means of course. Dad and I used wooden planks and a few jacks. Honestly should have dished out for some jack stands but that was in the past. Best option is a lift of course but work with what you got.

With the car up and the VSS in your hand, you will test to see if the issue is either the VSS or tran. gear. Start with the VSS, leave the harness on, have another set of eyes on the speedometer and get a power drill, figure out a way to spin up the VSS. Gently apply power to the handle to spin the VSS faster and faster but dont spin it excessively. If the problem reciprocates, find the Factory Service Manual (FSM) and get the EL/EC sections, inside both find the sections on speed sensor and speedometer. Follow through the procedure to see if there is a fault in the harness or if the VSS is jank.

If the VSS is fine then it would seem that the last culprit is the tran. gear. Give it an inspection to see if it is worn out. If it is, decide what your plan of action is (Keep reading). Otherwise, if it looks fine start the car and safely adjust it to 1st gear and let the car drive (car is safely elevated and second pair of eyes is in the driver's seat at this point). Once the car is running, inspect the gear: maybe it is looks lopsided.

At this point if you think the transmission is faulty, consider the cluster as a potential problem. The easiest way to see that it is is to remove your dash-cluster and replace it with a friend's borrowed cluster. You owe him/her a beer now. Verify if the cluster is at fault here with the above tests. The obvious decisions should now follow knowing the status of the entire system now.